# More Information I'm Sending With A Diagram - For The Hydraulic System

1. May 3, 2005

### Eng_Luqman

Hi ...
I attached with this text letter the mechanica system diagram that including or working by Hydraulic unit ... Its for holding about 8 tons , Metal Sheet's Coil .

So I asked about How To Choose The Suitable Pump For This System .

Will Be Thankfull For Your Help ... And Also For Those That They Answered My Questions ...

With My Best Wishes

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2. May 3, 2005

### FredGarvin

I don't want to come off as a jerk, but you have me a bit concerned with what you are asking. Your serious lack of required information provided shows that you are not familiar with designing hydraulic systems of any kind. There are a lot of questions and work that you need to answer/do before you get to a pump selection.

Let's start the list of the things that are immediately coming to mind:
- How far away will the pump be from the machine and reservoir?
- What source will drive the pump (electrical service)?
- What size of reservoir will you have?
- What is the full description of the loads that the part being held will see?
- How exactly is the part being held?
- What are the cylinder sizes?
- What is your system's maximum operating pressure and temperature?
- How fast/far must the cylinders extend and retract?
- What kind of tubing/fittings are you using?
- What kind of cooling will be available (water/air)?
- What kind of controls are you planning on using?

You MUST know what demands your entire system will put on your pump. That includes all losses due to piping and components (valves, heat exchangers, check valves, filters, accumulators, etc...). If you need a place to start, I guess you can start with:

$$HP = Q*p*.000583$$ where:
HP = Hydraulic Power required in HP
p = System pressure in psi
Q = Volumetric flowrate in gal/min

In the end, I suppose that if you size a relief large enough, you could grossly oversize the pump/motor to ensure that you have the required flow and pressure available for all of your components. That would mean you would need to know how to size a relief valve.

My first recommendation is that you either find a mentor or a good hydraulics book and start learning. Vickers put out a really good industrial hydraulics book that I recommend. I can't speak for other engineers here, but I am very leary of sizing any component or doing anyone's real world work for them. Especially when it is apparent that the end use will involve personnel safety. You do not want to screw around with high pressure and not understand what you are doing.

3. May 3, 2005

### brewnog

I'd second that.

I designed a hydraulic press last year while on an industrial placement. When it came to designing the actual hydraulics, I just made a circuit diagram and then got a professional hydraulics engineer in to specify the power pack. Sure, I'd done the numbers and knew what size pump was needed, but there was no way I was being held directly accountable for the design of the hydraulic system.

Having seen the aftermath of a pumping house accident where a hose had been incorrectly specified (rubber instead of steel), I have developed a healthy fear of high pressure systems. It's amazing just how much steel and concrete can be cut through by hydraulic oil.

I'd add that your pump selection will vary drastically depending on the desired operating cycle of your machine; this looks like the kind of application which won't be subject to continuous consecutive cycles, so the incorporation of accumulators might be a benefit.

4. May 4, 2005

### minger

For sizing Pressure Relieving Devices, see API 520, specifically part I (sizing and selection). I'm sure there are many different manufacturer's catalogs that you can look through to find one that fits your needs. Code states that for normal service the pressure relieving valve must be set at a pressure no greater than 5% the MAWP of the system. Don't quote me on that, I'm 85% sure that its 5% over.

I wish I could help ya more on the hydraulic part of it, but I'm not real experienced with it. Quote from a movie that is someone applicable in this situation, "Hell girl, I can't swim so you know what I do? I stay my black ass out the pool." - Gone in 60 Seconds. haha, anyways, I hope someone can help you out though.